Ringworm in live export dairy cattle

Summary

There is strong demand for Australian dairy heifers in China. The Chinese export protocol requires that cattle spend at least 30 days in pre-export quarantine, with multiple yardings required for disease testing and treatment. With susceptible young cattle from many different properties mixed together and lots of close physical contact, conditions during quarantine are ideal for ringworm spread. To date, all large shipments of cattle to China have had some cases of ringworm.

Ringworm is not life threatening – most cases heal by themselves, without treatment, in about eight weeks. However it causes significant economic loss to exporters. The Chinese veterinarians sent to oversee export preparation are quite sensitive to ringworm.

Cattle with severe or active lesions at the time of loading may be rejected from export. There is also a risk that ringworm developing at sea or after arrival in China will cause an incident that disrupts the market.

The primary aim of this project was to determine which fungi are most commonly involved and which treatments are likely to be most effective.

Skin scrapings were collected from ringworm affected cattle in six consignments exported to China during 2002. They were all identified as Trichophyton verrucosum.

Imidazole compounds are the topical treatment of choice for cattle with ringworm. Iodine and chlorine based preparations have a much lower efficacy. Imaverol is the only registered imidazole product that can be readily applied to cattle as a spray.

Treatment with an effective anti-fungal preparation will not induce a rapid clinical response. Regrowth of hair still takes some weeks. The most that can be expected is that established lesions develop no further, and that ringworm spread is contained.

The products of choice for disinfecting cattle yards and handling facilities are cationic alkyl dimethylbenzyl ammonium halides. There are a number of preparations available, with choice based on availability and price.

There is a cattle ringworm vaccine registered for use in Europe and Canada, but not in Australia. The vaccine has registration claims for both treatment and prevention of ringworm in cattle. Two vaccinations, at least 14 days apart, are required to establish long-term immunity. The vaccine appears to be both safe and effective.

Vaccination provides the best hope of consistently achieving very effective ringworm control. Registration in Australia is needed before the vaccine can be used. With industry support, restricted registration for export use only might be possible, using registration data already available in Europe. This should be actively explored.

A fact sheet about ringworm in cattle is needed, written in both Mandarin and English, so that sound technical information is available to the Chinese veterinarians overseeing export preparation.

Exporters sending cattle to China should routinely adopt best practice ringworm control procedures.